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Seven protesters have been arrested after clashing with police and fans of controversial British commentator Milo Yiannopoulos at his secret Sydney event.

The function venue, Le Montage in Lilyfield, was heavily guarded with mounted police, officers on bicycles, riot squad, marine police and police vans barricading the event last night after several arrests were made at his Victorian event the previous evening.

The Sydney venue wasn't revealed until an hour before it the event was scheduled to start and the surrounding streets were all closed off in the hours leading up to his scheduled speech.

Milo Yiannopoulos with Liberal Democrat Senator David Leyonhjelm.The man at the centre of protests in Melbourne last night has quickly made a name for himself through controversy. (AAP)

Yiannopoulos had earlier caused a stir in Canberra at a talk in Parliament House widely attended by self-proclaimed anti-establishment politicians including Senator Pauline Hanson and Coalition MP George Christensen.

Yiannopoulos's speeches on university campuses in the US have sparked violent protests, and he was banned from Twitter last year amid a barrage of racist abuse directed at Ghostbusters star Leslie Jones.

But he told the Parliament House gathering he was only fighting "fire with fire".

"The last guy to do that is now sitting in the Oval Office," he said.

Yiannopoulos's presence has sparked some ugly protests.

"When I talk about aggression I'm speaking about rhetoric. I don't believe in violence as a solution to problems."

Earlier, Senator Leyonhjelm said he wasn't aware of the broad scope of Yiannopoulos' controversial remarks.

"I think he's able to outrage people who I think are silly - lefties in general," Senator Leyonhjelm said.

"Causing outrage to those sorts of people seems to me sufficient reason to hear from him."

Left- and right-wing protesters last night clashed in Melbourne's inner-city suburbs over the commentator's presence.

Police charged two men with discharging a missile, and used litres of capsicum spray on the streets of Flemington ahead of the alt-right poster boy's talk at the Melbourne Pavilion.

Five police officers suffered minor injuries in the fracas.

The 33-year-old Yiannopoulos will follow his Sydney stopover with a trip to the Gold Coast to speak on Thursday.

A former senior editor for alt-right online publication Breitbart News, Yiannopoulos has earned a cult following online for his anti-feminist, anti-Muslim views, as well as his controversial stance on paedophilia.